Matrix t2*K(2) in Subspace 63 with Dimension 12

(K(2) is the second-order Grosse operator)

-3*t*U (Sqrt[3]*(-4*t^2 + U^2))/2 3*Sqrt[2]*t*U 0 0 -(Sqrt[6]*t^2) -(Sqrt[6]*t^2) (Sqrt[3]*t*U)/2 Sqrt[3/2]*t*U 0 Sqrt[3]*t*U 0
(Sqrt[3]*(-4*t^2 + U^2))/2 (-15*t*U)/2 -(Sqrt[3/2]*U^2) 0 0 (t*U)/Sqrt[2] -(Sqrt[2]*t*U) 4*t^2 0 0 t^2*(2 + U^2/(2*t^2)) -(U^2/Sqrt[2])
3*Sqrt[2]*t*U -(Sqrt[3/2]*U^2) -6*t*U 0 0 0 0 Sqrt[3/2]*t*U -(Sqrt[3]*t*U) 2*Sqrt[6]*t^2 0 0
0 0 0 (-25*t*U)/(6 + Sqrt[6]) Sqrt[5/6]*t*U 0 0 -(Sqrt[6 + Sqrt[6]]*t*U)/2 ((Sqrt[2] - 3*Sqrt[3])*t*U)/Sqrt[6 + Sqrt[6]] (-4*(1 + Sqrt[6])*t^2)/Sqrt[6 + Sqrt[6]] 0 0
0 0 0 Sqrt[5/6]*t*U (25*(-1 + Sqrt[6])*t*U)/(12 - 7*Sqrt[6]) 0 0 (3*(Sqrt[2] - 2*Sqrt[3])*t*U)/(2*Sqrt[18 - 3*Sqrt[6]]) (Sqrt[2/(6 - Sqrt[6])] + 3*Sqrt[3/(6 - Sqrt[6])])*t*U (4*(-1 + Sqrt[6])*t^2)/Sqrt[6 - Sqrt[6]] 0 0
-(Sqrt[6]*t^2) (t*U)/Sqrt[2] 0 0 0 -2*t*U t*U (4*t^2 - U^2)/Sqrt[2] 0 0 Sqrt[2]*t^2 0
-(Sqrt[6]*t^2) -(Sqrt[2]*t*U) 0 0 0 t*U -5*t*U 2*Sqrt[2]*t^2 -U^2 -(Sqrt[2]*t*U) Sqrt[2]*t^2 0
(Sqrt[3]*t*U)/2 4*t^2 Sqrt[3/2]*t*U -(Sqrt[6 + Sqrt[6]]*t*U)/2 (3*(Sqrt[2] - 2*Sqrt[3])*t*U)/(2*Sqrt[18 - 3*Sqrt[6]]) (4*t^2 - U^2)/Sqrt[2] 2*Sqrt[2]*t^2 (-7*t*U)/2 (t*U)/Sqrt[2] -U^2 (-3*t*U)/2 -((t*U)/Sqrt[2])
Sqrt[3/2]*t*U 0 -(Sqrt[3]*t*U) ((Sqrt[2] - 3*Sqrt[3])*t*U)/Sqrt[6 + Sqrt[6]] (Sqrt[2/(6 - Sqrt[6])] + 3*Sqrt[3/(6 - Sqrt[6])])*t*U 0 -U^2 (t*U)/Sqrt[2] -7*t*U 0 (-3*t*U)/Sqrt[2] t*U
0 0 2*Sqrt[6]*t^2 (-4*(1 + Sqrt[6])*t^2)/Sqrt[6 + Sqrt[6]] (4*(-1 + Sqrt[6])*t^2)/Sqrt[6 - Sqrt[6]] 0 -(Sqrt[2]*t*U) -U^2 0 -5*t*U 0 2*Sqrt[2]*t^2
Sqrt[3]*t*U t^2*(2 + U^2/(2*t^2)) 0 0 0 Sqrt[2]*t^2 Sqrt[2]*t^2 (-3*t*U)/2 (-3*t*U)/Sqrt[2] 0 -3*t*U Sqrt[2]*t*U
0 -(U^2/Sqrt[2]) 0 0 0 0 0 -((t*U)/Sqrt[2]) t*U 2*Sqrt[2]*t^2 Sqrt[2]*t*U -2*t*U